Hospital bed having alert light

ABSTRACT

A bed includes a frame, a controller coupled to the frame, and a patient position detection system coupled to the frame and coupled to the controller. The patient position detection system has at least three modes of operation of varying sensitivities for determining whether a person supported on the frame has moved by a sufficient amount to activate an alarm.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/154,553, filed Jun. 7, 2011, now U.S. Pat. No. 8,258,963, which is acontinuation of U.S. patent application Ser. No. 12/912,330, filed Oct.26, 2010, now U.S. Pat. No. 7,978,084, which is a continuation of U.S.patent application Ser. No. 11/851,535, filed Sep. 7, 2007, now U.S.Pat. No. 7,834,768, which is a continuation of U.S. patent applicationSer. No. 11/774,744, filed Jul. 9, 2007, now U.S. Pat. No. 7,986,242,which is a continuation of U.S. patent application Ser. No. 11/088,468,filed Mar. 24, 2005, now abandoned, which is a continuation of U.S.patent application Ser. No. 10/940,480, filed Sep. 14, 2004, nowabandoned, which is a continuation of U.S. patent application Ser. No.10/038,986, filed Nov. 19, 2001, now U.S. Pat. No. 6,791,460, which is acontinuation of U.S. patent application Ser. No. 09/737,111, filed Dec.14, 2000, now U.S. Pat. No. 6,320,510, which is a divisional of U.S.patent application Ser. No. 09/264,174, filed Mar. 5, 1999, now U.S.Pat. No. 6,208,250, the disclosures of all of which are herebyincorporated herein by reference in their entirety.

BACKGROUND SUMMARY OF THE INVENTION

The present invention relates to a patient position detection apparatusfor a bed. More particularly, the present invention relates to a bedexit and patient position detection apparatus which has multiple modesof operation for providing information to a caregiver regarding alocation of a patient on a support deck of the bed and for providing anindication when the patient has exited the bed.

When a patient is required to stay in a hospital bed at a hospital orother patient care facility, it is desirable for a caregiver to be ableto monitor the presence, absence, and location of the patient on the bedsupport surface and to monitor the patient's activity level. Caregiverswithin a hospital or other patient care facilities are continuouslyresponsible for more and more activities. One of these activities ismonitoring patients who need to be restricted to the bed or patientsthat are at a risk of falling or aggravating injuries if they exit thebed. Patients having certain patient profiles, such as confusion,weakness, or disorientation, are more likely to be injured or reinjuredif they exit the bed. Patients with certain types of medical conditionstherefore require monitoring of both their presence on the bed and theiror location on the support surface. In this instance, the presentinvention provides an alarm when the patient moves out of thepredetermined position on the bed, prior to exiting the bed.

Some patients are allowed by doctor's orders to move about freely on thebed in order to access the bed controls, a phone, or other items or toreposition themselves for comfort. In this situation, an alarm is onlyrequired if the patient totally exits the bed.

The present invention provides dual sensor mechanisms for detecting thelocation of the patient on the bed and for detecting bed exit.Therefore, the caregiver may select from various modes of operationdepending upon the patient condition and profile. The apparatus of thepresent invention detects the presence or absence of the patient on thebed and also detects the position of the patient on the support surface.Therefore, the present invention allows proper patient monitoring to beapplied at the discretion of the caregiver for the correct patientsituation.

The apparatus of the present invention utilizes two different sensortechnologies integrated into the support sections of the hospital bedframe and deck. A controller monitor inputs from both types of sensorsand, depending upon the mode selected by the caregiver, results in analarm or no alarm based on detected sensor conditions.

In an illustrated embodiment of the invention, a first set of sensorsincludes load cells mounted on a base frame of the bed to support aweigh frame. As weight is applied to the bed, such as when a patiententers the bed, the controller detects voltage changes from the loadcells. A second set of sensors is located below the patient. Thesesecond sensors are illustratively pressure sensitive sensors, such asresistive sensors which are located on the support deck or within themattress. As pressure is applied to these sensors, such as when apatient lies on the mattress, a resultant voltage corresponds to theamount of pressure applied to a particular sensor. As the patient movesabout the bed, sensor resistances change accordingly, thereby providingthe controller with data to analyze regarding patient positions.

Each sensor provides an input to the common controller and all of theinputs are evaluated by the controller. When certain weight distributionchanges are detected, an audible or visual alarm is activated. Thecriteria for activating the alarm is dependent upon the particular modeof operation for the overall system. Multiple modes of operation areselected by a switch, knob, button, etc. located on the bed, andpreferably on a siderail of the bed. It is understood that a controlpanel on a pendant or remote control input device electrically coupledto the controller may be used to select the modes.

In an out-of-bed mode, an alarm is activated only when a patientcompletely exits the bed. In an exiting mode, an alarm is activated whena patient is located at a pre-exit position near the sides or ends ofthe support surface of the bed. Finally, in a position mode, an alarm isactivated when a patient moves away from a head support surface on thedeck located beneath the patient's head and back, such as when thepatient has rolled against a siderail of the bed or has sat up in bed.Therefore, position mode provides an alarm earlier than exiting mode.

In the exiting mode and position mode, an alarm will also be activatedif the patient exits the bed. In other words, in exiting mode andposition mode, the out-of-bed detector is also used.

The alarm tones of the apparatus may be selected from a number ofvarious tone options. Different sounds or visual indicators may beprovided for each of the modes, if desired. In one illustratedembodiment, the patient positioning system is configured to deactivatethe alarm if the patient gets back into bed or returns to the correctposition on the bed. The apparatus also includes a button, switch, etc.located on the bed which will send a signal to reset or clear the “nursecall” alarm which is activated at a remote nurse station when a patientalarm is generated by the apparatus. This button allows the nurse toclear the remote bed exit/patient position alarm while at the bed afterresponding to the alarm. Currently, nurses have to clear the bedexit/patient position alarm by returning to the nurse call station or bydeactivating the alarm somewhere else in the hospital, other than at thebed. Another illustrated embodiment of the invention is configured toturn on the room lights when an alarm is activated.

According to an illustrated embodiment of the present invention, anapparatus is provided for detecting a position of a body on a supportsurface of a bed. The apparatus includes at least one first sensorcoupled to the bed and at least one second sensor located adjacent thesupport surface. The at least one first sensor has an output signalwhich is variable in response to changes in a weight applied to thesupport surface. The at least one second sensor has an output signalwhich is variable in response to changes in the position of the body onthe support surface. The apparatus also includes a controller havinginputs configured to receive the output signals from the first andsecond sensors. The controller is configured to monitor the outputsignals, to provide an indication of changes in the position of the bodyrelative to the support surface, and to provide an indication if thebody exits the support surface.

In the illustrated embodiment, the first and second sensors aredifferent types of sensors. The at least one first sensor isillustratively a load cell or other suitable sensor. The at least onesecond sensor is illustratively a resistive pressure sensor, acapacitance sensor, a piezoelectric sensor, or other suitable sensor.

The bed illustratively includes a base frame and a weigh frame. Theweigh frame is configured to support the support surface of the bed. Theat least one first sensor includes a plurality of load cells configuredto couple the weigh frame to the base frame. Each of the plurality ofload cells is electrically coupled to the controller.

The support surface of the bed illustratively includes a deck and amattress located on the deck. In one embodiment, the at least one secondsensor is coupled to the mattress. The at least one second sensor iseither coupled to a top or bottom surface of the mattress or locatedwithin an interior region of the mattress.

In another illustrated embodiment, the at least one second sensor iscoupled to the deck. The deck illustratively includes a head decksection, a seat deck section, a thigh deck section, and a leg decksection. The second sensors illustratively include at least one headsensor coupled to the head deck section, at least one seat sensorcoupled to the seat deck section, and at least one thigh sensor coupledto the thigh deck section.

In the illustrated embodiment, the head sensor is an elongated stripwhich extends in a direction parallel to a longitudinal axis of thedeck. The head sensor is located at a center portion of the head decksection. Two elongated thigh sensors are illustratively coupled to thethigh deck section. The elongated thigh sensors illustratively extend ina direction parallel to the longitudinal axis of the deck. The seatsensor is an elongated strip which is configured to extend in adirection transverse to the longitudinal axis of the deck. The secondsensors may further include at least one leg sensor coupled to the legdeck section.

The illustrated apparatus further includes an alarm coupled to thecontroller. The controller has a first mode of operation in which thealarm is activated by the controller only when the at least one firstsensor detects that the body has exited the bed, a second mode ofoperation in which the alarm is activated by the controller when the atleast one second sensor detects that the body has moved away from acentral portion of the support surface, and a third mode of operation inwhich the alarm is activated by the controller when the at least onesecond sensor detects that the body has moved away from a centralportion of a head section of the deck.

The illustrated apparatus further includes first, second, and third modeindicator lights located on the bed which correspond to the first,second, and third modes of operation of the controller, respectively.The controller is coupled to the first, second, and third mode indicatorlights. The controller is configured to illuminate the first modeindicator light when the controller is in the first operation mode, toilluminate the first and second mode indicator lights when thecontroller is in the second operation mode, and to illuminate the first,second, and third mode indicator lights when the controller is in thethird operation mode.

The illustrated apparatus includes a control panel coupled to thecontroller to permit a caregiver to select between the first and secondmodes of operation. The control panel is illustratively either coupledto a siderail of the bed, located on a pendant coupled to thecontroller, coupled to the controller by a remote control transmitter,or located elsewhere on the bed.

In an alternative embodiment of the present invention, the controller isconfigured to activate the alarm when the patient is out of apredetermined position on the support surface. The controller is alsoconfigured to detect when the body moves back into the predeterminedposition on the support surface and automatically deactivate the alarmupon detection of the body moving back into the predetermined positionon the support surface.

In yet another embodiment, the controller is configured to monitormovement of the body on the support surface. The controller isconfigured to generate an output signal if a predetermined amount ofmovement of the body is not detected within a predetermined period oftime.

In an illustrated embodiment, the controller includes an output coupledto a communication port to provide a nurse call alarm upon detection ofthe body moving out of a predetermined position on the support surfaceof the bed. A nurse call clear actuator is coupled to the bed. The nursecall clear actuator is configured to clear the nurse call alarm. Thecontroller also is configured to transmit an output signal through thecommunication port to a remote location over a communication network.

According to another illustrated embodiment of the present invention. Anapparatus is provided for detecting a position of a body on a supportsurface of a bed. The apparatus includes at least one sensor coupled tothe bed. The at least one sensor has an output signal which is variablein response to changes to in the position of the body on the supportsurface. The apparatus also includes an alarm and a controller having atleast one input configured to received the output signal from the atleast one sensor and an output coupled to the alarm. The controller hasat least two different modes of operation to monitor the position of thebody on the support surface and generate an alarm signal to activate thealarm if predetermined conditions are met. The apparatus furtherincludes a control panel coupled to the controller. The control panelincludes a key button and a separate mode button to permit a caregiverto change the mode of operation of the controller. The controller isconfigured to permit a caregiver to adjust the mode of operation bypressing the mode button only when the key button is also pressed.

The control panel is illustratively coupled to a siderail of the bed,located on a pendant coupled to the controller, coupled to thecontroller by a remote control transmitter, or located elsewhere on thebed. The illustrated control panel also includes an alarm volume controlbutton. The controller being configured to permit the caregiver toadjust the volume of the alarm using the volume control button only whenthe key button is also pressed. In other illustrated embodiments, thecontrol panel includes an actuator to permit a tone of the alarm to beselected from a plurality of different tones, and the controller isconfigured to turn on a room light wherein the alarm signal isgenerated.

In the illustrated embodiment, the controller has first, second andthird different modes of operation. The alarm is activated by thecontroller when different levels of patient movement on the supportsurface are detected for the first, second and third modes of operation.The apparatus also includes first, second, and third mode indicatorlights located on the control panel which correspond to the first,second, and third modes of operation of the controller, respectively.The controller is coupled to the first, second, and third mode indicatorlights. The controller is illustratively configured to illuminate thefirst mode indicator light when the controller is in the first operationmode, to illuminate the first and second mode indicator lights when thecontroller is in the second operation mode, and to illuminate the first,second, and third mode indicator lights when the controller is in thethird operation mode.

According to yet another illustrative embodiment of the presentinvention, a bed includes a base, a support surface coupled to the base,a controller configured to control an entertainment device including atleast one of a television, a radio, a stereo, a video player, and acomputer, and an entertainment control panel coupled to the controller.The entertainment control panel includes inputs to permit an operator tocontrol operation of the entertainment device. The apparatus alsoincludes a lockout switch coupled to the controller. The lockout switchis configured to disable the entertainment control panel when thelockout switch is actuated.

In the illustrated embodiment, an indicator light is coupled to thecontroller. The indicator light is illuminated when the lockout switchis actuated. The indicator light is illustratively coupled to a siderailof the bed spaced apart from the lockout switch. The lockout switch isillustratively coupled to a footboard of the bed. A cover is coupled tothe footboard. The lockout switch being concealed beneath the cover.

According to still another embodiment of the present invention, a bedincludes a base, a support surface coupled to the base, a controllerconfigured to control a plurality of functions including at least one ofa night light, a back light, a head articulation actuator, a kneearticulation actuator, a hi/lo actuator, and an entertainment device,and a control panel coupled to the controller. The control panelincludes a plurality of inputs to permit an operator to control theplurality of functions. The apparatus also includes a plurality oflockout switches coupled to the controller and an indicator located onthe bed spaced apart from the plurality of lockout switches. Thecontroller is configured to disable operation of selected functions bythe control panel upon actuation of corresponding lockout switches. Theindicator is configured to provide an indication when at least one ofthe lockout switches is actuated to disable operation of at least one ofthe functions.

Illustratively, the indicator is coupled to a siderail of the bed andthe plurality of lockout switches are located on a footboard of the bed.Each of the plurality of lockout switches illustratively includes aseparate light located adjacent the lockout switch to indicate when thelockout switch is actuated.

According to a further embodiment of the present invention, an apparatusis provided for aligning a first electrical connector electricallycoupled to a control panel located on a removable member of a bed with asecond electrical connector electrically coupled to a controller on thebed. The apparatus includes a first connector alignment apparatus havinga connector receiving portion configured to secure the first electricalconnector to the first connector alignment apparatus, a second connectoralignment apparatus having a connector receiving portion configured tosecure the second electrical connector to the second connector alignmentapparatus, a first fastener configured to couple the first connectoralignment apparatus to the removable member of the bed, and a secondfastener configured to couple the second connector alignment apparatusto a frame of the bed. One of the first and second connector alignmentapparatuses includes at least one alignment post, and the other of thefirst and second connector alignment apparatuses includes at least oneaperture configured to receive the alignment post therein as theremovable member is installed on to the frame of the bed to align thefirst and second electrical connectors before the first and secondconnectors are mated.

In the illustrated embodiment, the frame of the bed includes at leastone post extending away from the frame by a distance greater than aheight of the second connector alignment apparatus. The removable memberof the bed is formed to include an aperture configured to receive thepost on the frame of the bed to provide an initial alignment between theremovable member and the frame as the removable member is installed onto the frame. The first electrical connector includes at least onealignment post and the second electrical connector includes an apertureconfigured to receive the alignment post of the first electricalconnector therein to provide further alignment between the first andsecond electrical connectors.

In the illustrated embodiment, the first fastener is configured toprovide a rigid connection between the first connector alignmentapparatus and the removable member, and the second fastener isconfigured provide a loose connection between the second connectoralignment apparatus and the frame to permit limited movement of thesecond connector alignment apparatus relative to the frame. The frame ofthe bed is illustratively formed to include at least one aperture. Thesecond electrical connector alignment apparatus illustratively includesat least one retention post configured to be inserted into the at leastone aperture of the frame. The at least one aperture of the frame islarger than the at least one retention post to permit the limitedmovement of the second connector alignment apparatus relative to theframe of the bed.

Additional features and advantages of the invention will become apparentto those skilled in the art upon consideration of the following detaileddescription of illustrated embodiments exemplifying the best mode ofcarrying out the invention as presently perceived.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description particularly refers to the accompanying figuresin which:

FIG. 1 is a perspective view of a hospital bed which includes a patientposition detection apparatus in accordance with the present inventionand which includes a footboard having an electrical connector alignmentapparatus of the present invention;

FIG. 2 is an end view of the footboard of FIG. 1 illustrating furtherdetails of the electrical connector alignment apparatus;

FIG. 3 is an exploded perspective view of portions of the hospital bedof FIG. 1 illustrating a base frame, a weigh frame, an intermediateframe, a retracting frame, an articulating deck, a first set of sensorsfor detecting the weight of a patient on the deck, and a second set ofsensors located on the articulating deck for detecting the position ofthe patient on the deck;

FIG. 4 is a partial sectional view illustrating a load cell configuredto connect the weigh frame to the base frame;

FIG. 5 is a perspective view of a head end siderail which includes acontrol panel for operating the patient position detection apparatus ofthe present invention;

FIG. 6 is an enlarged view of the control panel of FIG. 5 which is usedto control the mode of operation of the patient position detectionapparatus and the volume of the alarms generated by the detectionapparatus;

FIG. 7 is a block diagram illustrating the control electronics of thepatient position detection apparatus;

FIG. 8 is a top plan view of the articulating deck of the bed with thesecond set of sensors mounted on the deck;

FIGS. 9 and 10 are flow charts illustrating a main loop of stepsperformed by the controller for monitoring inputs from the control paneland the first and second sets of sensors to control operation of thepatient position detection apparatus in a position mode, an exitingmode, and an out-of-bed mode;

FIG. 11 is a flow chart illustrating steps performed by the controllerin the position mode;

FIG. 12 is a flow chart illustrating steps performed by the controllerin the exiting mode;

FIG. 13 is a flow chart illustrating steps performed by the controllerin the out-of-bed mode;

FIG. 14 is a perspective view of a first electrical connector alignmentapparatus configured to be coupled to the footboard of the bed;

FIG. 15 is a perspective view of a second electrical connector alignmentapparatus configured to be coupled to the retracting frame of the bed;and

FIG. 16 is an exploded perspective view illustrating the first andsecond electrical connector apparatuses with electrical connectorsinstalled therein and located on the footboard and retracting frame,respectively.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring now to the drawings, FIG. 1 illustrates a hospital bed 10 ofthe present invention. The bed 10 includes a base frame 12 having aplurality of casters 14 and brake/steer control pedals 16 mountedadjacent each of the casters 14. Details of the operation of thebrake/steer control mechanism are disclosed in U.S. patent applicationSer. No. 09/263,039, now U.S. Pat. No. 6,321,878, which is herebyincorporated by reference.

As best shown in FIG. 3, the bed 10 includes a weigh frame 18 coupled tothe base frame 12, an intermediate frame 19 coupled to the weigh frame18, a retracting frame 20 coupled to the intermediate frame 19, and anarticulating deck 22 coupled to the intermediate frame 19 and theretracting frame 20. Brackets 21 on opposite sides of frame 20 areconfigured to be coupled between the head section 106 and the thighsection 110 of deck 22 with suitable fasteners (not shown).

Referring again to FIG. 1, the bed 10 includes a headboard 24 mountedadjacent a head end 26 of the bed 10 and a footboard 28 mounted to theframe 20 adjacent a foot end 30 of bed 10. Bed 10 further includes apair of head end siderails 32 and a pair of foot end siderails 34mounted to the articulating deck 22 on opposite sides of the bed 10.Further details of head end siderail 32 are illustrated in FIG. 5.Siderails 32 and 34 are coupled to the articulating deck 22 in aconventional manner using a connector mechanism 35 best shown in FIG. 5.The siderails 32 and 34 are movable from a lowered position shown inFIG. 1 to an elevated position (not shown) located above a top surface36 of mattress 38. Mattress 38 is located on articulating deck 22 forsupporting a patient thereon.

The footboard 28 includes a plurality of buttons, knobs, switches orother controls 40 for controlling various functions of the bed 10.Controls 40 are located on a top inclined panel 42 and a bottom inclinedpanel 44 on the footboard 28. A cover 46 is pivotably coupled to thefootboard 28 by a pivot connection 48 so that the cover can be pivoteddownwardly to conceal at least the controls 40 located on the topinclined panel 42.

One of the controls on the footboard 28 is illustratively a lockoutbutton 61 for entertainment functions which are controlled by patientinput control panels on the bed 10. In other words, a caregiver canpress button 61 to lock out entertainment functions on the bed 10. Anindicator light is provided adjacent the entertainment lockout control61 to provide an indication when the entertainment lockout 61 isactivated. When the entertainment lockout 61 is activated, the patientcannot turn on the television, radio, stereo, video player, computer orother entertainment device typically available on the bed or in theroom. The entertainment lockout control 61 is illustratively locatedbelow the cover 46 on the footboard 28. It is understood, however, thatthe entertainment lockout may be located at other positions on the bed.

The bed 10 also includes a plurality of lockout switches 63 which areillustratively located on the footboard 28. It is understood that thelockout switches 63 may be located at any other position on the bed 10.The lockout switches 63 are coupled to the controller 50 to permit acaregiver to lock out selected functions which are normally controlledby the patient. Using patient controls that are typically located on thehead end siderails 32. For example, lockout switches 63 may deactivatecontrols for a night light, a back light, head or knee articulation, ahi/lo mechanism, or the entertainment devices discussed above. Inaddition, a master lockout switch is provided to lock out the head andknee articulation and the hi/lo control mechanism controls.

Panel 42 illustratively includes an indicator light (not shown) adjacenteach of the lockout switches 63 to provide an indication when aparticular lockout switch 63 is pressed. In addition, the bed 10includes a separate lockout indicator light 65 located at a location onthe bed 10 spaced apart from the lockout switches 63. In the illustratedembodiment, the separate lockout indicator light 65 is located on thehead end siderail 32 as shown in FIG. 5. Indicator light 65 provides thenurse with a visual indication that one of the lockout switches 63 hasbeen pressed.

Footboard 28 also includes side bumpers 66 and apertures 68. Apertures68 provide handles to facilitate movement of the bed 10. Illustratively,headboard 24 and footboard 28 are made from a plastic material using ablow molding process. It is understood, however, that the headboard 24and footboard 28 may be made from other materials and from otherprocesses, if desired.

The controls 40 on the footboard 28 are electrically coupled to acontroller 50 shown in FIG. 3. The controller 50 and other bedelectronics are illustratively mounted on frame 20. A first connectoralignment apparatus 52 is coupled to the footboard 28 and a secondconnector alignment apparatus 54 is coupled to the frame 20. As shown inFIGS. 2 and 3, footboard 28 is formed to include apertures 56 whichslide over posts 58 on the frame 20 during installation of the footboard28 onto the frame 20 in the direction of arrow 60 in FIG. 3. Posts 58and apertures 56 therefore provide initial alignment between thefootboard 28 and the frame 20. First and second connector alignmentapparatuses 52 and 54 provide further alignment for male and femaleelectrical connectors 62 and 64, respectively, as discussed in detailbelow with reference to FIGS. 14-16.

The patient position detection apparatus of the present invention usestwo different types of sensors 70, 104. A first set of sensors 70 isused to detect when a patient exits the bed 10. A second set of sensors104 is used to determine a position of the patient on the deck 22 of thebed 10. In the illustrated embodiment, the first type of sensors includeload cells 70 which are mounted at the four corners of the weigh frame18. Details of the mounting of the load cells 70 between the base frame12 and the weigh frame 18 are illustrated in FIGS. 3 and 4. Base frame12 includes side frame members 72 and transverse frame members 74extending between the side frame members 72. Weigh frame 18 includes apair of hollow side frame members 76. Load cells 70 are well known. Loadcells 70 typically include a plurality of strain gauges located within ametal block.

As best shown in FIG. 4, a mounting ball 78 is coupled to the load cell70. Illustratively, mounting ball 78 includes a threaded stem which isscrewed into threads in the load cell 70. Mounting ball 78 is locatedwithin an aperture 80 formed in a mounting block 82. Mounting blocks 82are secured to the transverse frame members 74 by suitable fasteners 84at the four corners of the base frame 12. A mounting bar 86 is coupledto an arm 88 of load cell 70 by fasteners 90. Mounting bar 86 is thensecured to a top surface 92 of side frame member 76 of weigh frame 18 bysuitable fasteners 94 and washers 96. Mounting bar 86 is not coupled toarm 98 of load cell 70. Therefore, load cell 70 may be deflecteddownwardly in the direction of arrow 100 when weight is applied to theweigh frame 18. Such deflection in the direction of arrow 100 changes anoutput voltage which provides an indication of weight change on theweigh frame. Load cells 70 are coupled to a signal conditioner 53 bywires 102. The signal conditioner 53 is then coupled to the controller50 on the bed 10 by wires 102.

Although the specification and claims of this application refer to acontroller 50, it is understood that the bed 10 will typically includeseveral controllers which control different functions on the bed. Thesecontrollers may be located at any location on the bed and are notlimited to the location illustrated in FIG. 3. The controllers 10typically are microprocessor based controllers. Output signals fromvarious devices may need to be conditioned prior to being coupled to thecontroller. For instance, analog signals may need to be converted todigital signals for processing by the microprocessor of the controller.Therefore, the word controller is used broadly to include any type ofcontrol circuitry necessary to process the output signals and producethe desired control outputs or signals.

A second set of sensors 104 is illustrated in FIGS. 3 and 8.Articulating deck 22 includes a head deck section 106, a seat decksection 108, a thigh deck section 110, and a leg deck section 112. Thesecond set of sensors 104 includes a head section sensor 104 coupled tohead deck section 106 by fasteners 116. Sensor 114 is elongated andextends along a longitudinal axis 118 of the deck 22. Seat sensor 120 iscoupled to seat deck section 108 by fasteners 116. Sensor 120 extends ina direction transverse to the longitudinal axis 118. Thigh sensors 122and 124 are coupled to thigh deck section 110 by fasteners 116. Thelocations of sensors 114, 120, 122, 124 are further illustrated in FIG.8.

Illustratively, sensors 114, 120, 122, and 124 are resistive pressuresensors available from Interlink Electronics. The resistive pressuresensors are formed in strips which can be cut to any desired length. Thesensor strips are illustratively adhered to a stiffener and then sealedwithin a protective outer sleeve or cover made from a wipable material.Fasteners 116 are illustratively rivets which secure the sensors 114,120, 122, and 124 in position on the deck 22 as best shown in FIG. 8.Sensors 114, 120, 122, and 124 are coupled to the controller 50 on thebed 10 by wires 126.

As pressure on the sensors 114, 120, 122, and 124 increases, resistanceof the sensors is lowered. By processing the output signals from sensors114, 120, 122, and 124, the controller 50 determines the position of thepatient on the deck 22. In particular, the controller 50 determines whenthe patient moves away from a central portion of the bed and too closeto the side edges 23 or 25 on the deck 22. Controller 50 then providesan indication that the patient is at risk of exiting the bed.

Using the two different types of sensors 70 and 104, the patientposition detection apparatus of the present invention is capable ofoperating in several different modes to assist the caregiver withtracking the patient position on the bed 10. In an out-of-bed mode, onlysensors 70 are used to activate an alarm when a patient completely exitsthe bed. In a second exiting mode, both sets of sensors 70, 104 areused. An alarm is activated when a patient is located at a position nearthe sides 23, 25 of deck 22 or on the deck 22 near the head end 26 orfoot end 30. In other words, a pre-exit alarm is sounded when thepatient moves outside a central portion of the deck 22 on the bed 10. Ina third position mode, both sets of sensors 70, 104 are also used. Analarm is activated when a patient moves away from the head sensor 114 onthe deck 22 as discussed below.

FIG. 7 is a block diagram illustrating the electronic control componentsof the patient position detection apparatus. As discussed above, thefirst and second sensors 70 and 104 are each coupled to the controller50. The controller 50 processes signals from the first and secondsensors 70, 104 as discussed in detail below to provide various controlfunctions. A caregiver control panel 130 is mounted on the bed 10 tocontrol operation of the patient position detection apparatus.Preferably, the caregiver control panel 130 is mounted on the head endsiderail 52 as best shown in FIG. 5. The control panel 130 may also beon a pendant or on a remote control device electrically coupled to thecontroller 50. The caregiver control panel 130 includes control buttons,switches, knobs, etc. for setting the particular type of tone for theaudible alarm and for setting a volume of the alarm for each of thedetection modes as illustrated at block 132. In addition, the caregivercontrol panel 130 includes control buttons, switches, knobs, etc. to setthe particular type of detection mode for the apparatus as discussedbelow. Inputs from the caregiver control panel 130 are transmitted tothe controller 50. Controller 50 also transmits signals to the caregivercontrol panel 130 to control indicator lights 136 on the caregivercontrol panel 130.

If an alarm condition is detected by controller 50 as discussed below indetail, controller 50 controls either audible or visual local alarms 138within the room or on the bed 10. Controller 50 may also be used to turnon the room lights 140 when an alarm condition is detected. Finally, thecontroller 50 activates a nurse call alarm 142 to send an indication ofthe alarm condition to a nurse station located at a remote location.

The apparatus of the present invention further includes a nurse callreset or clear button 144 located on the bed 10. This clear button 144sends a signal to controller 50 to clear the nurse call 142 alarm oncethe nurse call 142 alarm has been activated at the remote nurse callstation. Nurse call clear button 144 permits the caregiver to clear orreset the remote patient alarm while at the bed 10 after responding tothe alarm condition. Currently, caregivers must cancel the nurse callbed exit alarm 142 by returning to the nurse call station or bydeactivating the alarm somewhere else in the hospital, other than at thebed 10. Button 144 permits the caregiver to clear the nurse call bedexit alarm 142 after responding to the alarm condition at the bed 10.Controller 50 is also coupled to a communication network 55 so that thecontroller 50 can transmit output signals to a remote location.

In an alternative embodiment of the present invention, controller 50 isprogrammed to deactivate the local alarm 138 if the patient returns tobed 10 or returns to a correct position on the bed 10 depending upon themode selected. This feature may encourage the patient to return to thecorrect position on the bed 10 since the alarm will be deactivated whenthe patient returns to the correct position. The nurse call alarm 142typically remains activated so that the caregiver may still respond tothe alarm, even if the local audible and visual room alarm 138 isdeactivated.

FIG. 6 illustrates further details of the caregiver control panel 130which is illustratively located on the head end siderail 132. Controlpanel 130 includes a key button 150, a mode control button 152, and avolume control button 154. In order to adjust the detection mode orvolume of the alarm, the caregiver must depress the key button 150 andhold it down while depressing the desired mode button 152 or volumebutton 154. With the key button 150 held down, the caregiver can scrollthrough the modes of operation by pressing the mode button 152. Separateindicator LEDs are provided to indicate which mode is selected. ThePosition Mode is indicated by LED 156, the Exiting Mode is indicated byLED 158, and the Out-of-Bed Mode is indicated by LED 160. If none of theLEDs 156, 158, 160 is lit, the patient position detection apparatus isoff.

If the Position Mode is selected, all three LEDs 156, 158, and 160 arelit. If the Exiting Mode is selected, LEDs 158 and 160 are lit. If theOut-of-Bed Mode is selected, only LED 160 is lit. By providing adifferent number of indicator lights for each of the three modes, acaregiver can tell which mode is selected in the dark.

By requiring the depression of both the key button 150 and the modebutton 152 or volume button 154 and by placing these buttons 150, 152,154 on the caregiver side of the siderail 32, the patient is deterredfrom changing modes or volumes. The caregiver can change the volume ofthe alarm between a high setting, a medium setting, and a low setting bypressing the key button 150 and simultaneously pressing the volumebutton 154. Subsequent presses of the volume button 154 change thevolume to different levels. Indicator LEDs 162, 164, and 166 areprovided for the high, medium, and low volumes, respectively. If thehigh volume level is selected, all three LEDs 162, 164, and 168 are lit.If the medium volume level is selected, LEDs 164 and 168 are lit. If thelow volume level is selected, only LED 168 is lit. By providing adifferent number of indicator lights for each volume level, a caregivercan tell the volume level for the alarm in the dark. When the patientposition detection apparatus is off, all the volume LEDs 162, 164, and168 are off.

When a local alarm condition is detected by controller 50 as discussedbelow. An appropriate LED for Position Mode, Exiting Mode, andOut-of-Bed Mode will flash on the control panel 130 to indicate an alarmcondition for that mode. More than one of the LEDs 156, 158, and 160 canflash. For instance, in Position Mode, the Position Mode LED 156 maybegin to flash when an alarm condition is detected by the Position Mode.Since the Out-of-Bed Mode is also run in Position Mode, the Out-of-BedLED 160 may also be flashing if the patient has exited the bed.

Caregiver control panel 130 also includes an indicator LED 170 toprovide an indication that the bed 10 is not down. This indicator LED170 is lit when the deck 22 is not in its lowest position relative tothe floor. In addition, caregiver panel 130 includes an indicator LED172 which provides an indication when the brake on the casters 14 is notset. When positioned in a room, the bed 10 is typically set so that thedeck 22 is in its lowest position and the brake is set. Therefore,indicator LEDs 170 and 172 provide the caregiver with an indication thatthese conditions are not met.

FIG. 8 shows the illustrative arrangement of the sensors 114, 120, 122,and 124 on the articulating deck 22. It is understood that otherarrangements of the second set of sensors 104 may be used in accordancewith the present invention. In addition, additional sensors may beprovided such as a sensor 125 located on the leg deck section 112.Although the second sensors 104 are illustratively resistive sensors, itis understood that other types of sensors may be used in accordance withthe present invention. For example, capacitance sensors such as shown inU.S. Pat. No. 5,808,552 or in U.S. patent application Ser. No.09/031,749, now U.S. Pat. No. 6,067,019 which are incorporated herein byreference, may be used as the second sensors. In addition, apiezoelectric sensor such as disclosed in U.S. application Ser. No.09/263,038, now U.S. Pat. No. 6,252,512, which is hereby incorporated byreference, may also be used. In another embodiment, the sensors 104 arecoupled to a stop or bottom surface of the mattress 38 or are locatedwithin an interior region of the mattress 38.

FIGS. 9-12 are flow charts illustrating operation of the controller 50of the present invention and each of the three patient positiondetection modes. The main software loop of the controller 50 isillustrated in FIGS. 9 and 10. The main loop begins at block 200 of FIG.9. Controller 50 first updates the status of the indicator lights 136 oncontrol panel 130 or elsewhere as illustrated at block 202. Controller50 then determines whether the patient detection system is on at block204. If the detection system is not on, controller 50 advances to block230 as illustrated at block 205. If the patient detection system is on,controller 50 checks the mode of the detection system as illustrated atblock 206. Specifically, controller 50 determines whether the detectionsystem is in position mode as illustrated at block 208, exiting mode asillustrated at block 210, or out-of-bed mode as illustrated at block212.

If the controller is in position mode as illustrated at block 208 orexiting mode as illustrated at block 210, the controller 50 will run thecontrol loops for these modes as discussed below. After running thepositioning mode loop or the exiting mode loop, the controller 50 willalso run the out-of-bed mode loop when the controller is set in positionmode or exiting mode. In other words, if the detection system is on, theout-of-bed mode will always be checked.

Controller 50 then determines whether the mode was just activated atblock 214. If the particular mode was not just activated, the controller50 advances to block 246 of FIG. 11 if the system is in position mode asillustrated at block 216. If the particular mode was not just activated,controller 50 advances to block 264 of FIG. 12 if the system is inexiting mode as illustrated at block 218. If the particular mode was notjust activated, controller 50 advances to block 278 of FIG. 13 if thesystem is in out-of-bed mode as illustrated at block 220.

If the mode was just activated at block 214, controller 50 reads all thesensor values from the first and second sets of sensors 70 and 104 asillustrated at block 222. Controller 50 then determines whether thesensor values are within the preset specifications as illustrated atblock 224. In the position mode, controller 50 is only concerned withthe head sensor 114. Therefore, in position mode, the output from headsensor 114 is checked. The output value from sensor 114 is withinspecification if the head sensor 114 output signal corresponds to arange of weights between 50-450 lbs. Therefore, for position mode, thesensor 114 is typically not within specification if the head sensor 114is not plugged in, shorted, or if a patient is not on the bed 10.

For exiting mode, controller 50 checks all the load cells 70 and sensors114, 120, 122, and 124. To be within specification for exiting mode, theweight range detected by load cells 70 must be within a predeterminedrange based on average human weights. Controller 50 also determineswhether any of the sensors 114, 120, 122, or 124 are not plugged in orare shorted. In the out-of-bed mode, controller 50 only looks at loadcells 70 to make sure that at least a predetermined minimum weightreading is obtained in order to indicate that a patient is on the bed10.

If the values read at block 222 are not within specifications,controller 50 will send a local alarm as illustrated at block 226 sothat the caregiver can investigate the problem as illustrated at block226. Controller 50 then turns the detection system off as illustrated atblock 227 and advances to block 230 as illustrated at block 229. If theretrieved sensor values are within the specifications at block 224,controller 50 stores all the sensor values in memory 51 as illustratedat block 228. Controller 50 then advances to block 230 as illustrated atblock 229.

In the illustrated embodiment, the key button 150 on control panel 130is a hardware switch. If the key button 50 is not pressed, thecontroller 50 does not receive the signal from the mode button 152 orthe volume button 154. Therefore, if the key button is not pressed asillustrated at block 232, controller 50 returns to block 200 asillustrated at block 244. If the key button 150 and the mode button 152are pressed as illustrated at block 234, the controller 50 will receivean input based on the mode button press. If the key button 150 and thevolume button 154 are pressed as illustrated at block 236, thecontroller 50 will receive an input signal from the volume button 154press. If the key button 150, the mode button 152, and the volume button154 are all pressed as illustrated at block 238, the controller 50 willreceive input signals from both the mode button press and the volumebutton press. If the key button and at least one other button arepressed at blocks 234, 236, and 238, controller 50 will update the modeand volume settings in memory 51 as illustrated at block 240. Controller50 then returns to block 200 as illustrated at block 244.

Operation of the controller 50 in position mode is illustrated beginningat block 246 of FIG. 11. Controller 50 first reads the current value ofhead sensor 114 as illustrated at block 248. The current head sensorvalue is abbreviated as CV. Next, controller 50 retrieves the storedvalue for head sensor 114 which was stored in memory 51 at block 228 asillustrated at block 250. The stored sensor value is abbreviated as SV.Controller 50 then determines a scaler value based upon the stored headsensor value. In the illustrated embodiment, an 8 bit A/D converter isused to convert the output from the sensors 104. Therefore, the value SVranges from 1-256 in the illustrated embodiment. Smaller values of SVindicate larger weight on the sensors 104. It is understood that thisrange could be varied depending upon the particular A/D converter used.Therefore, the range of 1-256 is only for illustrative purposes.Controller 50 sets the scaler value as illustrated in the table at block252. The scaler value remains constant until the mode is reactivated.Next, controller 50 calculates the acceptable range for the current headsensor value (CV) as illustrated at block 254. The acceptable range is:

Controller 50 determines whether the current head sensor value CV iswithin the acceptable range as illustrated at block 256. If so,controller 50 determines that the patient is in the proper position onthe deck and returns to block 230 as illustrated at block 262. If thecurrent head sensor value is not within the acceptable range at block256, controller 50 determines whether a timer has expired at block 258.If not, controller 50 advances back to block 230. If the timer hasexpired, controller 50 determines that the patient is out of positionand activates the local alarms 138 as illustrated at block 260.Controller 50 also activates a nurse call alarm 142, and may turn on theroom lights 140 at block 260. Controller 50 then advances to block 278and runs the out-of-bed mode check as illustrated at block 262.

Operation of the patient detection system in exiting mode is illustratedbeginning at block 264 in FIG. 12. Controller 50 advances to block 264from block 218 in FIG. 9. In exiting mode, controller 50 first runs thepositioning mode loop as illustrated at block 266. In other words, thecontroller 50 uses head sensor 114 to check the patient's position usingthe flow chart discussed above in reference to FIG. 11. Controller 50determines whether the current head sensor value CV is within theacceptable range as illustrated at block 268. If so, controller 50determines that the patient is in the proper position and advances toblock 278 to run the out-of-bed mode check as illustrated at block 276in FIG. 12.

If the head sensor value is not within the acceptable range at block268, controller 50 runs a sensor test for seat sensor 120 and thighsensors 122 and 124 using a similar test as in FIG. 11. Scaler valuesmay be adjusted for the different sensors 120, 122, and 124, ifnecessary. Scaler values are selected by applying a known load above aparticular sensor location and taking an output reading. Next, apredetermined distance from the sensor is selected at which point it isdesired to activate the alarm. The known weight is than moved to thatdesired alarm location and another output reading is taken. The scalervalue is calculated the percentage change between the output of thesensor when the known weight applied directly over the sensor and theoutput of the sensor when the known weight applied at the predetermineddistance perpendicular to the sensor.

Controller 50 then determines whether two of the three remaining sensors120, 122, and 124 are within acceptable ranges as illustrated at block272 by comparing the current sensor values to ranges based on thecorresponding stored sensory values. If so, controller 50 determinesthat the patient is in an acceptable position on the deck 22 andadvances at block 230 as illustrated at block 276. If two of the threesensors are not within the acceptable ranges at block 272, controller 50determines that the patient is out of position and updates the localalarms 238, activates the nurse call alarm 142, and may turn on the roomlights 140 as illustrated at block 274. Controller 50 then advances toblock 230 as illustrated at block 276. In exiting mode, the patientposition detection apparatus of the present invention permits thepatient to move around more on the deck 22 before an alarm is activatedcompared to the position mode. Therefore, position mode is the mostsensitive setting for the patient position detection apparatus of thepresent invention.

It is understood that other configurations may be provided for thelocations of sensors 104. A different number of sensors 104 may be used.The sensors 104 may be mounted at different locations on the deck 22, onthe mattress 38, or elsewhere on the bed 10.

Operation of the patient position detection system in the out-of-bedmode is illustrated beginning at block 278 in FIG. 13. Controller 50advances to block 278 from block 220 in FIG. 9. In the out-of-bed mode,controller 50 detects an average current weight of the patient asillustrated at block 280. For instance, the controller 50 can take fourreadings from each load cell 70 and divide by four to get an averagecurrent weight. Next, controller 50 retrieves the stored initial weightfrom memory 51 as illustrated at block 282. Controller 50 subtracts thestored weight from the current weight as illustrated at block 284.

Next, controller 50 determines whether the weight on the bed 10 detectedat block 280 has increased or decreased by more than 30 lbs. compared tothe initial stored weight retrieved at block 282. If the weight has notchanged by more than 30 lbs., controller returns to block 230 asillustrated at block 294. If the weight has changed by more than 30 lbs.at block 286, controller 50 determines whether a timer has expired atblock 288. If the timer has not expired, controller 50 advances to block230 as illustrated at block 294. If the timer has expired at block 288,the controller 50 determines whether the difference calculated at block284 is less than −30 lbs. at block 290. If so, controller 50 determinesthat the patient has exited the bed 10 and updates the local alarms 138,the nurse call alarm 142 and may turn on the room lights 140 asillustrated at block 292. Controller 50 then returns to block 230 asillustrated at block 294.

If the difference is not less than −30 lbs. at block 290, controller 50determines whether the difference calculated at block 284 is greaterthan 30 lbs. as illustrated at block 296. If so, controller 50determines that substantial additional weight has been added to the bedand updates local alarms 138 only as illustrated at block 298. The nursecall alarm 142 may also be activated, if desired. Controller 50 thenadvances to block 230 as illustrated at block 294. If the difference isnot greater than 30 lbs. at block 296, controller 50 clears the localalarm only at block 300 and then advances to block 230 as illustrated atblock 294.

It is understood that the 30 lbs. threshold value for the out-of-bedmode may be adjusted upwardly or downwardly depending upon the weight ofthe patient. In other words, if the patient is particularly heavy, the30 lb. threshold may be increased, for example.

It is understood that the patient detection apparatus of the presentinvention may have more than three modes of operation if desired. Theseparate modes may have different sensitivity levels.

The out-of-bed mode of the present invention may be armed with thepatient in the bed 10. In some beds having scales, the patient must beremoved in order to determine a tare weight of the bed prior to thepatient getting into the bed in order to arm the bed exit detector. Inthe out-of-bed mode of the present invention, removing the patient fromthe bed is not required in order to arm the bed exit detection system.

The patient position detection system of the present invention may bequickly switched from a normal bed exit system in which an alarm isgenerated only when a patient exits the bed to a predictive bed exitsystem in which an alarm is generated when a patient moves away from acenter portion of the bed. In an embodiment of the invention, the outputsignals from the first and second set of sensors 70, 104 are monitoredand stored, either at the bed 10, or at a remote location to recordmovements of the patient. The controller 50 or a controller at theremote location monitors the sensor output values to determine whetherthe patient is moving on the bed 10. In one embodiment, the controller50 or controller at a remote location generates a caregiver alert signalor alarm if the patient has not moved on the bed within a predeterminedperiod of time. Therefore, the caregiver can go to the bed 10 and rotatethe patient in order to reduce the likelihood that the patient will getbed sores. For example, if the patient hasn't moved for a predeterminedperiod of time, such as two hours, a signal is generated advising thecaregiver to move the patient. If the sensors 70, 104 and controllerdetect that the patient has moved within the predetermined period, thenthere is no need for the caregiver to go turn the patient. Therefore, nosignal is generated. This feature saves caregiver time and reduces thelikelihood of injuries due to unnecessary rotation of a patient who hasbeen moving.

In another embodiment of the present invention, the output signals fromthe four sensors 70 located at the corners of the base frame 12 are usedto provide an indication when one of the frames or the deck hits anobstruction when moving from the high position to a low position. Inparticular, the processor 50 determines when an output signal from oneof the sensors 70 at the corners generates a negative value or a greatlyreduced weight reading within a short period of time. This rapid changein the output signal indicates that an obstruction has been hit.Therefore, controller 50 can provide an output signal to stop the hi/lomechanism from lowering the frames and deck. An alarm signal is alsoprovided, if desired.

In another embodiment of the present invention, the controller 50 isconfigured to transmit data to a nurse station located at a remotelocation over the communication network 55. This data illustrativelyincludes information related to at least one of patient weight, thepatient's position on the support surface of the bed 10, a bed exitindicator, the mode of operation of the patient position detectionapparatus, a brake not set indicator, a bed not down indicator, or otherdata related to the status of the bed or the status of the patient. Thispermits the nurse to detect the information related to the status of thebed or the status of the patient at the central nurse station withouthaving to check each bed separately.

FIGS. 14-16 further illustrate the connector alignment apparatus of thepresent invention. The first connector alignment apparatus 52 isillustrated in FIG. 14, and the second connector alignment apparatus 54is illustrated in FIG. 15. Connector alignment apparatus 52 isconfigured to receive a first pair of electrical connectors 62 shown inFIG. 16 which include a housing 304 having a first pair of spaced-apartflanges 306 and a second pair of spaced-apart flanges 308. Flanges 308are each formed to include an aperture 310. Connectors 302 include aplurality of electrical terminals 312 extending away from housing 304.Alignment posts 313 extend from housing 304 of connector 62 further thanterminals 312. The terminals 312 are electrically connected toconductors of a cable 314. Cable 314 of connectors 62 are connected tocontrols 40. Connector alignment apparatus 54 is configured to receivefemale electrical connectors 64. Those numbers referenced by numbers onconnectors 62 perform the same or similar function. Connectors 64include female socket contacts 318 configured to receive terminals 312of connector 302. Illustratively, cables extending from connectors 64are coupled to the controller 50 on bed 10.

Referring now to FIG. 14, connector alignment apparatus 52 includes abase plate 320 having outwardly extending alignment posts 322 located atopposite ends. Posts 322 each include tapered head portions 324.Alignment apparatus 52 includes a pair of connector receiving portions326. Connector receiving portions 326 each include a pair of centerposts 328. Each post 328 includes a pair of spring arms 330. Each springarm 330 has a head portion 332 including a ramp surface 334 and a bottomlip 336. Each connector receiving portion 326 also includes a pair ofposts 338.

Electrical connectors 62 are installed into the connector receivingportions 326 by locating the apertures 310 on flanges 308 over the posts338 and pushing the connector 62 toward base 320. Flanges 306 engageramp surfaces 334 of heads 332 and cause the spring arms 330 to bedeflected. Once the flanges 306 move past the heads 332, heads 332 thenmove over flanges 306 to retain the connectors 302 within the connectoralignment apparatus 52 as best shown in FIG. 16.

Second connector alignment apparatus 54 is best illustrated in FIG. 15.The alignment apparatus includes a body portion 340 having a pair ofdownwardly extending alignment posts 342. Body portion 340 is formed toinclude apertures 344 at opposite ends. Apertures 344 are configured toreceive the posts 322 of first connector alignment apparatus 52 asdiscussed below. Lead-in ramp surfaces 346 are formed around theapertures 344. Body portion 340 further includes a pair of connectorreceiving portions 348 which function the same as connector receivingportions 326 described above. Reference numbers the same as in FIG. 14perform the same or similar function. Apertures 310 formed in flanges308 of connectors 64 are inserted over the posts 338 of the connectorreceiving portions 348. The connectors 64 are then pushed downwardly todeflect the heads 332 until the lips 336 move over flanges 306 to lockthe connectors 64 within the housing 340 as discussed above.

The first connector alignment apparatus 52 and the second connectoralignment apparatus 54 each may include a key shown diagrammatically atlocations 349 and 351, respectively. Certain beds have differentfeatures which are controlled by controller 50 and actuated by controls40 on the footboard. Therefore, different footboards 28 may be requireddepending upon the particular type of bed 10 being used. The keys 349and 351 on the first and second connector alignment apparatuses 52 and54 only permit connection between an appropriate type of footboard 28for the particular bed 10. Therefore, the keys 349 and 351 ensure thatthe right type of footboard 28 is attached to the bed 10.

First connector alignment apparatus 52 is rigidly coupled within arecessed portion 350 formed in footboard 28 as best shown in FIG. 16.The base 320 is secured to the footboard 28 by a fastener 352 whichextends through an aperture 354 formed in the base 320. The secondconnector alignment apparatus 54 is loosely connected to an end surface356 of the frame 20. A fastener 358 is configured to extend through anoversized central opening 360 formed in housing 340. Posts 342 atopposite ends of the housing 340 are located within apertures 362 formedin the surface 356 of the frame 20. Housing 340 is therefore not rigidlycoupled to frame 20 and can float slightly due to the oversizedapertures 362 and the oversized aperture 360.

During installation of the footboard 28 on to the frame 20, initialalignment is provided by posts 58 on frame 20 extending into theapertures 56 formed in the footboard 28. As the footboard 28 movesdownwardly over the posts 58, the posts 322 on first connector alignmentapparatus 52 enter the apertures 344 in the second connector alignmentapparatus 54. Tapered surfaces 324 on posts 22 and tapered surfaces 346of apertures 344 facilitate insertion of the posts 322 into theapertures 344. Since the housing 340 of second connector alignmentapparatus 54 can float on the frame 20, the housing 340 moves intoproper alignment with the first connector alignment apparatus 52 as thefootboard 28 is installed. This ensures proper alignment betweenconnectors 62 and 64. Typically, connectors 62 and 64 include furtheralignment posts 313 and apertures 315, respectively, which mate to makesure that each of the terminals 312 line up with the socket contacts318. Therefore, the connector alignment apparatus of the presentinvention includes a combination of posts 58 on the frame 20 which matewith aperture 56 on the footboard 28, posts 322 on the first connectoralignment apparatus 52 which mate with apertures 344 on the secondconnector alignment apparatus 54, and posts 313 on connectors 62 whichmate with apertures 315 on the connectors 64 to provide furtheralignment.

Although the invention has been described in detail with reference tocertain illustrated embodiments, variations and modifications existwithin the scope and spirit of the invention as described and as definedin the following claims.

1. A bed comprising: a frame including a lower frame and an upper framemovable between a raised position and a lowered position relative to thelower frame, a plurality of casters coupled to the lower frame, abraking system operable to brake and unbrake the casters, a controllercoupled to the frame, a patient position detection system which hasmultiple modes of operation from which to select for determining alocation of a patient relative to the frame, each mode of the multiplemodes of operation having a different sensitivity so that a differentamount of patient movement is required before an alarm condition isconsidered to exist, and at least one alert light coupled to the frameand coupled to the controller, the controller operating to change astate of the at least one alert light in response to at least one of theupper frame not being in the lowered position and the casters not beingbraked by the braking system.
 2. The bed of claim 1, wherein the frameincludes a plurality of barriers including a plurality of siderails, aheadboard and a footboard, the at least one alert light being coupled toone of the barriers.
 3. The bed of claim 2, wherein the barrier to whichthe at least one alert light is coupled also carries at least one userinput of the patient position detection system.
 4. The bed of claim 3,wherein the at least one user input of the patient position detectionsystem is usable to select which of the multiple modes of operation thepatient position detection system operates.
 5. The bed of claim 3,wherein the at least one user input of the patient position detectionsystem is usable to select a volume at which an audible alarm of thepatient position detection sounds when the alarm condition associatedwith a selected one of the multiple modes of operation is detected. 6.The bed of claim 2, wherein the alert light is coupled to at least oneof the siderails of the plurality of siderails.
 7. The bed of claim 1,wherein the multiple modes of operation includes first, second, andthird modes, the first mode of operation resulting in the alarmcondition being considered to exist in the event the first mode is theselected mode and the patient moves by a first amount, the second modeof operation resulting in the alarm condition being considered to existin the event the second mode is the selected mode and the patient movesby a second amount greater than the first amount, and the third mode ofoperation resulting in the alarm condition being considered to exist inthe event the third mode is the selected mode and the patient moves athird amount greater than the second amount.
 8. The bed of claim 7,wherein the third mode of operation results in the alarm condition beingconsidered to exit in the event the patient exits the frame.
 9. The bedof claim 7, wherein the patient position detection system includesfirst, second, and third mode indicator lights which correspond to thefirst, second, and third modes of operation of the patient positiondetection system, respectively, and the indicator lights indicatingwhich mode of the first, second, and third modes has been selected. 10.The bed of claim 1, wherein the at least one alert light comprises afirst alert light to indicate whether the upper frame is not lowered anda second alert light to indicate that the casters are not braked. 11.The bed of claim 10, further comprising at least one third light toindicate the selected mode of the multiple modes of the patient positiondetection system.
 12. The bed of claim 11, further comprising at leastone fourth light to indicate a volume at which an audible alarm of thepatient position detection system is to sound in the event of the alarmcondition of the selected mode of operation being detected.
 13. The bedof claim 1, wherein the frame includes a footboard having user inputsthat are usable to provide commands to the controller.
 14. The bed ofclaim 13, wherein the footboard is decouplable from the remainder of theframe and the user inputs are decoupled from the controller when thefootboard is decoupled from the remainder of the frame.
 15. The bed ofclaim 1, wherein the patient position detection system includes aplurality of sensors and signals from the plurality of sensors are usedto determine whether to activate an alarm based on the signals and aselected mode of operation.
 16. The bed of claim 15, wherein each of theplurality of sensors has an electrical resistance that varies with theposition of a patient relative to the frame.
 17. The bed of claim 15,wherein the plurality of sensors includes at least one load cell. 18.The bed of claim 15, wherein a weight of a patient supported by theframe is determined based on signals generated by the plurality ofsensors.
 19. The bed of claim 18, further comprising a footboard coupledto the frame and a display coupled to the footboard, the display beingoperable to display the weight of the patient.
 20. The bed of claim 1,wherein the controller is configured to send a signal to activate atleast one light spaced from the bed in response to the alarm conditionbeing detected.